The present invention relates generally to chucks for use with drills or with electric or pneumatic power drivers. More particularly, the present invention relates primarily to a chuck of the keyless type which may be tightened or loosened by hand or by actuation of the driver motor.
Both hand tool drivers and electric or pneumatic tool drivers are well known. Although twist drills are the most common tools used with such drivers, screw drivers, nut drivers, burrs, mounted grinding stones and other cutting or abrading tools may also be used. Since the tool may have shanks having various diameters or polygonal cross sections, the device is provided with a chuck that is adjustable over a relatively wide range. The chuck may be attached to the driver by a threaded or tapered bore.
A wide variety of chucks have been developed in the art. In one form, three jaws spaced circumferentially approximately 120.degree. apart from each other are constrained in angularly disposed passageways in a body. The body is attached onto the drive shaft and is configured so that rotation of the body in one direction relative to a constrained nut engaging the jaws forces the jaws into gripping relationship with a cylindrical tool shank, while rotation in the opposite direction releases the gripping relationship. Such a chuck may be keyless if it is rotated by hand. One example of such a chuck is disclosed in U.S. Pat. No. 5,125,673 entitled "non-impact keyless chuck" which is commonly assigned to the present assignee and the entire disclosure of which is incorporated by reference herein.
Despite the success of keyless chucks such as set forth in U.S. Pat. No. 5,125,673, varying configurations of keyless chucks are desirable for a variety of applications. Existing bearing arrangements in chucks are designed to take a thrust load and to eliminate friction between the nut and the body in the axial direction. These bearings are sometimes caged and may have separate top and bottom thrust races. A chuck having an improved bearing configuration to minimize radial as well as axial stresses is disclosed in U.S. Pat. No. 5,348,318, the entire disclosure of which is incorporated by reference herein.